verb (retrofits, retrofitting, retrofitted)

Heat pump water heaters can be purchased as integral units with built in water storage tanks or as add-ons that can be retrofitted to an existing water heater tank.

Because of the amount of wiring involved, the work is best done while a house is under construction and the walls are open - retrofitting this much cable, unless you don't object to exposed conduit, can add considerably to the cost.

There are many techniques depending on whether the home is under construction or being retrofitted to eliminate noise pollution.